Not all includes detected

[ARamsey118]

Using the code here, and running :YcmGenerateConfig, several includes appear to be missing. Errors such as "implicit declaration of function 'kzalloc' " are reported, but 'kzalloc' is defined in linux/slab.h, as noted by the comment. Adding the flag '-I/usr/scr/linux-headers-4.4.0-21/include' appeared to fix most errors on Xubuntu, including the kzalloc one, but a similar flag on Archlinux, '-I/lib/modules/4.5.4-1-ARCH/build/include/linux' did not.